LaTeX.org

Here you find the MWE:

\documentclass[12pt, classica, cucitura]{toptesi}
\usepackage{toptesi}
\usepackage{amsmath, amsthm, amssymb, amsfonts, enumerate, dlfltxbcodetips}
\usepackage{natbib}
\selectlanguage{italian}
\newtheorem{theorem}{Teorema}
\begin{document}
\begin{theorem}
Let
\begin{enumerate ...

Hi all!
I have a problem with enumerating items in the theorem environment.
The output that the enumerate command produce has italic numbers, and
I want them to be without any formatting.

Here you can find my preamble:

\documentclass[12pt, a4paper]{report}
\usepackage{toptesi}
\usepackage{amsmath ...